Journal of Organic Chemistry 2009-12-18

Synthesis of 1,4-dichloro-1,3-butadienes by rhodium complex catalyzed reaction of terminal alkynes with trichloroacetyl chloride.

Taigo Kashiwabara, Kouichirou Fuse, Takeshi Muramatsu, Masato Tanaka

Index: J. Org. Chem. 74(24) , 9433-9, (2009)

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Abstract

Chlorinative dimerization of terminal alkynes with trichloroacetyl chloride as chlorine donor proceeds in the presence of rhodium catalysts to give (Z,Z)-1,4-dichloro-1,3-butadienes stereoselectively. Ligand screening has revealed that reactions using sterically bulky and electron-donating ligands like trimesitylphosphine are high yielding. The reaction is compatible with a range of functional groups to give the title compounds nearly quantitatively in most cases. A mechanistic possibility involving coupling of beta-chloroalken-1-yl intermediate has been discussed.